1884. ] Botany. 67 
numbered among its founders and most active members Rev. Dr. 
James Laurie, Dr. Alex. McWilliams and Dr. John A, Brereton, 
while Dr. Bigelow, of Boston, and Doctors Darlington and Bar- 
ton, of Pennsylvania, were honorary members. Four years after 
the dissolution of this society Dr. Brereton published his “ Flore 
Columbianz Prodomus,” in the preface of which he briefly alludes 
to it. This work is still extant, and an analysis of its contents 
may be found in Mr. Ward's recently published “ Flora of Wash- 
ington.”? 
This allusion of Dr. Brereton was about all that was known of 
the history of the botanical society prior to the discovery of the 
above-mentioned document, which, containing as it does the 
names of.all its members, its constitution and by-laws, and a 
careful record of all its work in the study of a then unknown and 
still remarkable flora, possesses great interest for local botanists. 
Mr. Ward promised that it should be ultimately so disposed of as 
to render it safe from the vicissitudes of either private individu- 
als or ephemeral societies. : 
HYBRIDISM IN SprroGyra.—An interesting case of hybridism 
between individuals of two distinct species of Spirogyra came un- 
der my observation at Ames, Ia., in August, 1883. The plants of 
this genus are the familiar pond scums which occur everywhere 
in ponds and ditches as green stringy growths floating or attached 
to sticks and stones. Each plant is a long cylinder of cells, and 
in the latter there may be seen, under a moderate power of the 
microscope, the beautiful spiral arrangement of the chlorophyll 
bodies. Sexual reproduction takes place by the union of the pro- 
toplasm of two cells. Two plants happening to lie side by side, 
bud out small short branches which, growing towards each other, 
finally touch at their tips and then fuse into tubes. Through these 
tubes the protoplasm from one cell runs into and unites with that 
in the other. Asa result of this union of protoplasm a resting 
spore (technically a zygospore) is formed. This process may be 
observed by any one almost any time during the summer, by the 
aid of a microscope, and there are few things which are more in- 
structive to the beginner in vegetable physiology, who would gain 
some insight into the real nature of sexual reproduction. 
_ Inthe case of hybridism under consideration, the two species 
involved were Spirogyra majuscula and S. protecta. These species 
differ from one another so much that there can be no question as 
to their distinctness. In S. majuscula (A and A’ in the figure) 
there are many very slightly coiled spirals of chlorophyll, the 
nucleus of the cell is very evident, and the partitions between the 
cells are plane; in S. protecta (B and B’ in the figure).on the con- 
trary, there is but one closely coiled spiral of chlorophyll, the nu- 
_* Guide to the Flora of Washington and its Vicinity. Bulletin No. 22, U. S. Na- 
tional Museum. Washington, Government Printing Office, 1881. 
